The manufacture of glass articles (containers, sheets, etc.) involves handling various molten substances at temperatures in excess of 1400° C. In particular, glass forming materials may be melted and reacted to form molten glass in a vessel such as a furnace, melter, or tank. The molten glass is typically held in the vessel so that it can be refined and homogenized to achieve a consistent composition that is suitably free from defects before it can be thermally conditioned and formed into the desired article. The glass-forming material may be composed of a wide range of ingredients. For example, in the manufacture of soda-lime-silica glass articles, the glass-forming materials can include virgin raw materials (e.g., quartz silica, soda ash, limestone, etc.), pre-reacted glass reaction materials such as sodium silicate (Na2O.SiO2) and wollastonite (CaSiO3), cullet, and a variety of other materials like fining agents, colorants, oxidizers, reducers, etc., as is well known in the art. Other glass batch formulations are also known for making soda-lime-silica glass as well as other types of glass including borosilicate glass.
Molten glass and, in particular, glass precursor melts, are quite chemically active. The term “molten glass,” as used herein, refers to the final molten composition of the glass-forming materials that will eventually be processed into a glass article of the same chemical makeup. For example, in the manufacture of soda-line-silica glass articles, the attained molten glass has a chemical composition that comprises about 60 wt. % to about 80 wt. % silica (SiO2), about 8 wt % to about 18 wt. % sodium oxide (Na2O), about 5 wt. % to about 15 wt. % calcium oxide (CaO), and optionally about 0-2 wt. % alumina (Al2O3), about 0-4 wt. % magnesia (MgO), about 0-1.5 wt. % potash (K2O), about 0-1 wt. % iron oxide (Fe2O3), about 0-0.5 wt. % titanium oxide (TiO2), and about 0-0.5 wt. % sulfur trioxide (SO3). The chemical harshness of the molten glass can be attributed to some or all of the various oxide compounds it contains. Glass precursor melts can be just as, and in certain instances, more chemically harsh than molten glass. The term “glass precursor melt,” as used herein, refers to intermediate molten phases of the molten glass—for example, molten sodium silicate and other early-stage molten phases—that are combined and assimilated with the molten phases of the other glass-forming materials to become molten glass. Put differently, glass precursor melts are intermediate contributing components of the final molten glass composition.
The vessel(s) in which the glass-forming materials are melted and the resultant molten glass is refined and homogenized are typically lined with refractory bricks formed of zirconia, mixture of zirconia, alumina, and silica, or some other suitable refractory material. These types of traditional liners—while effective for some time—are not everlasting. They are susceptible to corrosion and erosion over time by molten glass and glass precursor melts, albeit at a slow enough rate to permit glass production to occur on a commercial scale. Eventually, when the vessel liner wears out, the entire vessel has to be taken off-line so that some or all of the liner can be replaced or repaired. This is a time-consuming and expensive process. Other structures that are made from similar refractory materials and are exposed to molten glass and glass precursor melts, such as impellers, face the same types of challenges.
One or more embodiments set forth in the present disclosure may provide a robust nanocomposite material that can effectively withstand the degenerative effects of molten glass and glass precursor melts for a substantial period of time. The nanocomposite material can be used to construct any kind of structure that will come in contact with molten glass and/or glass precursor melts such as, for example, a vessel liner or an impeller.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A nanocomposite material in accordance with one aspect of the disclosure includes a cermet substrate and a glass reaction material overlying the cermet substrate. The cermet substrate may include a refractory metal matrix and ceramic particles embedded in the refractory metal matrix. The overlying glass reaction material may be the reaction product of molten glass and a surface of the cermet substrate in an inert environment.
In accordance with another aspect of the disclosure, there is provided a vessel in which glass-forming materials are melted and reacted to form molten glass. The vessel comprises an outer shell and a protective nanocomposite liner located inside the outer shell. The protective nanocomposite liner defines a vessel space where the glass-forming materials are melted and reacted. The protective nanocomposite liner includes, but is not limited to, a cermet substrate and a glass reaction material overlying a side of the cermet substrate that is adjacent to the vessel space. The cermet substrate may include a refractory metal matrix and ceramic particles embedded in the refractory metal matrix and the glass reaction material may be the reaction product of molten glass and the cermet substrate in an inert environment.
In accordance with yet another aspect of the disclosure, there is provided a structure for contacting molten glass, glass precursor melts, or both. The structure is made by a process that includes the steps of (1) providing a cermet substrate that comprises a refractory metal matrix and ceramic particles embedded in the refractory metal matrix, and (2) contacting a side of the cermet substrate with molten glass in an inert environment to form a glass reaction material over the cermet substrate.